Pressure seal for butterfly valves

ABSTRACT

A butterfly valve embodying an improved pressure seal. The valve includes a valve body having a fluid passage in which is a valve disc journaled for rotation between open and closed positions. A two member seal is arranged to contact the valve disc when the latter is in the closed position and the two members of the seal are constructed so that fluid under pressure may pass between an interface of the two members to the radially outermost side thereof to drive disc engaging, sealing noses of each of the members into firm sealing engagement with the disc.

United States Patent [191 Fawkes PRESSURE SEAL FOR BUTTERFLY VALVESInventor:

Donald G. Fawkes, Aurora, Ill.

Henry Pratt Company, Aurora, Ill.

Assignee:

Filed: Oct. 20, 1971 Appl. No.: 191,026

[56] I References Cited 7 9 UNITED STATES PATENTS 9/ 1968 Fawkes ..25l/308 X 10/1970 Frazier ..25 1 I306 [451 Apr. 10,1973

3,076,631 2/1963 Grove ..251/173 3,409,269 11/1968 Fawkes ..251/173xPrimary Examiner-Harold W. Weakley v Attomey-Hofgren, Wegner et a1.

[ ABSTRACT A butterfly valve embodying an improved pressure seal. Thevalve includes a valve body having a fluid passage in which is a valvedisc joumaled for rotation between open and closed positions. A twomember seal is arranged to contact the valve disc when the latter is inthe closed position and the two members of the seal are constructed sothat fluid under pressure may pass between an interface of the twomembers to the radially outermost side thereof to drive disc engaging,sealing noses of each of the members into firm sealing engagement withthe disc.

8 Clairm, 3 Drawing Figures This invention relates to valves and, moreparticularly, butterfly valves having improved pressure seals.

There are in existence a number of butterfly valve constructionsemploying so-called pressure seals.

Typically in such constructions, a resilient sealing member is disposedin annular relation to a fluid passage in such a position as to engagethe periphery of a valve disc joumaled within the passage for movementbetween open and closed positions. To augment the seal provided by thenatural resilience of the sealing member against the valve disc when thelatter is in a closed position, there is generally provided a pressurespace behind the seal and some means of fluid communication between thepressure space and the high pressure side of the valve so that when thesame is closed, fluid under pressure is directed to the pressure spaceto exert an inwardly directed pressure against the seal which in turnurges the latter into firm engagement with the periphery of the disc.

A principal difficulty with such constructions is the fact thatsediment'in the fluid will tend to accumulate in the pressure space torender, over a period of time, the pressure seal partially or whollyinoperative.

Some constructions have the further disadvantage in requiring machiningoperations to provide the flow path from the high pressure side of thevalve to the pressure space, which machining operations are costly andcontribute significantly to the cost of the valve.

SUMMARY OF THE INVENTION It is the principal object of the invention toprovide a new and improved pressure seal in a butterfly valve. Moreparticularly, it is an object of the invention to provide a new andimproved pressure seal which is constructed in such a way that long-runoperability is not affected by sediment and which does not requirecostly machining operations to provide a high pressure fluid path to apressure space behind a sealing member.

The exemplary embodiment of the invention achieves the foregoing objectin a valve construction including a valve body having a fluid passageextending therethrough and a valve disc joumaled therein for rotationbetween open and closed positions by means of a sealing constructionformed of two side-by-side sealing members disposed within a groove inthe passage and each having a nose extending into the passage tosealingly engage the periphery of the valve disc when the latter is in aclosed position. At least a portion of the outermost sides of thesealing members are 'free to move somewhat relative to the outermostportion of the groove with the result that fluid under pressure may passthrough the interface between the two sealing members to exert pressureagainst the outermost sides thereof thereby driving the noses inwardlyinto firm engagement with the periphery of the disc.

According to the preferred embodiment, the sealing members are heldwithin the groove by a setbody of plastic; according to anotherembodiment, an epoxy resin cast in situ. To insure freedom of movement,as mentioned in the preceding paragraph, the outermost surfaces of thesealing members are coated with a mold release agent.

Other objects and advantages will become apparent from the followingspecification taken in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of a butterflyvalve made according to the invention;

FIG. 2 is a fragmentary sectional view illustrating the improved seal ofthe invention; and

FIG. 3 is an extremely enlarged section illustrating a portion of theseal and depicting, in slightly exaggerated form, the pressure sealingeffect obtained.

DESCRIPTION OF THE PREFERRED EMBODIMENT An exemplary embodiment of abutterfly valve embodying the invention is illustrated in FIG. 1 and isseen to include a valve body, generally designated 10, including a fluidpassage 12 extending therethrough. Within the passage 12 is a valve disc14 from which oppositely extending trunnions (not shown) are directedinto bores in journal housings 16 and 18 on the valve body 10 for thepurpose of journaling the disc 14 for rotation between an open positionas shown and one approximately therefrom at which the fluid passage 12is closed.

The upper journal housing 18 mounts an operator 20 which may be eithermanual or motor driven for the purpose of rotating the disc 14 betweenthe aforesaid open and closed positions.

With reference now to FIG. 2, within the passage 12 in the valve body10, there is provided an annular groove 22. The radially outermost sideportions of the groove 22 are widened as at 24 for securing purposes aswill be seen.

Disposed within the annular groove 22 is a pair of sealing elements 26and 28. The sealing elements 26 and 28 are formed of a flexible materialsuch as rubber and may be formed in strips by extrusion processes of aconventional character to have identical cross sections. Once thusformed, the resulting strip may be cut into appropriate lengths and theends of each strip joined to define the circular sealing members adaptedto sealingly engage the disc 14 about the entire periphery of thelatter.

Each of the sealing elements 26 and 28 includes a sealing surface in theform of a nose 30 that projects into the passage 12 to sealingly engagea sealing surface 32 on the periphery of the disc 14. Additionally, eachsealing element 26 and 28 includes a peripheral groove 34 and the twosealing elements 26 and 28 are disposed within the annular groove 22 sothat their corresponding grooves 34 are oppositely located. That is,they are disposed within the groove 22 such that their grooved surfacesare remote from each other.

The sealing elements 26 and 28 are held in place by a set body ofplastic 36. According to the preferred embodiment, the set body ofplastic 36 is an epoxy resin cast in situ and introduced into the groove22 by a passage 38 in the valve body 10 provided for that purpose, whilethe sealing members 26 and 28 are located within the groove 22 in theposition shown. By reason of the greater width of the groove 22 at 24and the grooves 34, it will be appreciated that sealing elements 26 and28 will be firmly held in place when the plastic sets up.

In order to provide for pressure sealing, the radially outermost surface40 of each of the sealing elements 26 and 28 is free to move inwardlyaway from the set body of plastic 36. According to the preferredembodiment, such freedom is obtained by providing each of the surfaces40 with a coating 42 of a suitable mold release agent prior to theintroduction of the liquid plastic into the bore 36.

The general fabrication procedure is as follows. The sealing members 26and 28 are located in the groove 22 and the disc 14 is then moved to aclosed position to hold the sealing members in place. Liquid plastic isthen introduced through the bore 38 to fill up that portion of thegroove 22 unoccupied by the seals 26 and 28. The plastic will flow intothe grooves 34 in each of may be sealed at an appropriate point, notshown, to

maintain the pressure and the plastic cured in place. After the plasticis cured, the valve will be ready for use and it will be appreciatedthat the noses 30 will be urged against the disc 14 at apressureapproximately equal to that applied on the liquid plastic duringthe forming process. In addition, the radially outermost surfaces 40 ofthe seals 26 and-28 will be isolated from fluid in the passage exceptthrough the interface 44.

' Additional pressure sealing is attained in use as follows. Withreference to FIGS. 2 and 3, it will be appreciated that one of thesealing members 26 and 28 on the high pressure side-in a fluid systemwill permit some of the fluid .under pressure to flow to the interface44 between the two sealing members 36 and 28. From this point, it willflow along the interface 44 to the radially outermost surfaces 40 of thesealing members 26 and 28 and will act thereagainst to increase thepressure with which the noses 30 are urged against the sealing surfaces32 of the disc 14. While the material used to fabricate the sealingmembers 26 and 28 will generally be substantially incompressible, somemovement may occur, which movement is shown in an exaggerated form indotted lines in FIG. 3. Thus, whenever the pressure'in the line exceedsthe pressure with which the plastic was introduced into the recess 22during manufacture, an increased, positive pressure seal will beprovided.

It will be appreciated from the foregoing description of the structureand operation of a valve made according to the invention that thepressure seal cannot be rendered partly or wholly ineffective bysedimentation as there is no path or appreciable size by which the fluidcontrolled can convey sediment to the pressure responsive surfaces ofthe sealing members 26 and 28. Similarly, there is no need to provide aspecial pressure conveying passage from the high pressure side of thevalve to the pressure responsive surfaces of the sealing elements 26 and28 and thus, a valve made according to the invention may be fabricatedwithout requiring special machining operations as has been the case withcertain prior valve structures.

I claim:

- l. A butterfly valve construction comprising:

a valve body having a fluid passage extending therethrough; a valve discjoumaled within said passage for rotation between open and closedpositions; and sealing means within said body about the periphery ofsaid passage for sealingly engaging the periphery of said disc when saiddisc is in said closed position, said sealing means comprising a pair offlexible members disposed in side-by-side relationship and eachincluding a nose portion located inwardly of the periphery of saidpassage for sealingly engaging the periphery of said disc, a body of setplastic material at least partially radially outwardly of said flexiblemembers firmly locating said members in a position to sealingly engagesaid disc when said disc is in said closed position, at least a portionof the outermost peripheral surface of said members being free to moveinwardly and away from said body of set plastic whereby fluid underpressure may flow through the interface between said members to theinterface of said outermost peripheral surfaces and said body of setplastic material to exert pressure against said members to urge the noseof at least one of said members into flrm sealing engagement with theperiphery of said disc when said disc is in said closed position.

2. The valve of claim 1 wherein said body of set plastic material isformed of an epoxy resin cast in situ, and said outermost peripheralsurfaces are coated with a mold release agent.

3. The valve of claim 1 wherein each of said members includes aperipheral groove in the side thereof remote from the other of saidmembers, said valve body includes an annular groove radially outwardlyof said passage and opening on said passage, said annular groovereceiving said members and said set body of plastic.

4. The valve of claim 3 wherein said set body of plastic is cast in situand said outermost peripheral surfaces are coated with a mold releaseagent.

5. A butterfly valve construction comprising:

a valve body having a fluid passage extending therethrough; an annulargroove within said valve body and opening about said fluid passage; avalve disc joumaled within said passage for rotation between open andclosed positions; and sealing means within said annular groove about theperiphery of said passage for sealingly engaging the periphery of saiddisc whensaid disc is in said closed position, said sealing meanscomprising a pair of abutting flexible members, both within said groove,each having a portion extending from the groove inwardly into saidpassage to sealingly engage the periphery of said disc when said disc isin said closed position, and each further having a pressure responsivesurface opposite said portion and adapted to be subjected to fluid underpressure in a conduit with which said valve may be used, said fluidunder pressure flowing through the interface of said flexible members tosaid pressure responsive surfaces; and means retaining said flexiblemembers within said groove.

6. A butterfly valveaccording to claim 5 wherein each of said flexiblemembers includes a groove on a side thereof intermediate'said pressureresponsive surplastic within said annular groove, said pressureresponsive surfaces being free for movement relative to said set body ofplastic.

8. A butterfly valve construction according to claim 7 wherein saidpressure responsive surfaces include a coating of a mold release agent.

1. A butterfly valve construction comprising: a valve body having afluid passage extending therethrough; a valve disc journaled within saidpassage for rotation between open and closed positions; and sealingmeans within said body about the periphery of said passage for sealinglyengaging the periphery of said disc when said disc is in said closedposition, said sealing means comprising a pair of flexible membersdisposed in side-by-side relationship and each including a nose portionlocated inwardly of the periphery of said passage for sealingly engagingthe periphery of said disc, a body of set plastic material at leastpartially radially outwardly of said flexible members firmly locatingsaid members in a position to sealingly engage said disc when said discis in said closed position, at least a portion of the outermostperipheral surface of said members being free to move inwardly and awayfrom said body of set plastic whereby fluid under pressure may flowthrough the interface between said members to the interface of saidoutermost peripheral surfaces and said body of set plastic material toexert pressure against said members to urge the nose of at least one ofsaid members into firm sealing engagement with the periphery of saiddisc when said disc is in said closed position.
 2. The valve of claim 1wherein said body of set plastic material is formed of an epoxy resincast in situ, and said outermost peripheral surfaces are coated with amold release agent.
 3. The valve of claim 1 wherein each of said membersincludes a peripheral groove in the side thereof remote from the otherof said members, said valve body includes an annular groove radiallyoutwardly of said passage and opening on said passage, said annulargroove receiving said members and said set body of plastic.
 4. The valveof claim 3 wherein said set body of plastic is cast in situ and saidoutermost peripheral surfaces are coated with a mold release agent.
 5. Abutterfly valve construction comprising: a valve body having a fluidpassage extending therethrough; an annular groove within said valve bodyand opening about said fluid passage; a valve disc journaled within saidpassage for rotation between open and closed positions; and sealingmeans within said annular groove about the periphery of said passage forsealingly engaging the periphery of said disc when said disc is in saidclosed position, said sealing means comprising a pair of abuttingflexible members, both within said groove, each having a portionextending from the groove inwardly into said passage to sealingly engagethe periphery of said disc when said disc is in said closed position,and each further having a pressure responsive surface opposite saidportion and adapted to be subjected to fluid under pressure in a conduitwith which said valve may be used, said fluid under pressure flowingthrough the interface of said flexible members to said pressureresponsive surfaces; and means retaining said flexible members withinsaid groove.
 6. A butterfly valve according to claim 5 wherein each ofsaid flexible members includes a groove on a side thereof intermediatesaid pressure responsive surface and said portion, said flexible membersbeing located within said annular groove such that said side grooves areoppositely located from each other, said retaining means including meansfixed to said valve body and within the side grooves of the flexiblemembers.
 7. A butterfly valve construction according to claim 5 whereinsaid retaining means comprises a body of set plastic within said annulargroove, said pressure responsive surfaces being free for movementrelative to said set body of plastic.
 8. A butterfly valve constructionaccording to claim 7 wherein said pressure responsive surfaces include acoating of a mold release agent.